I've mastered hardware, learned Linux fundamentals, and started learning basic programming (Javascript, Lua, Python, HTML-5, and CSS). But I'm now at a dead end. I don't feel experienced enough to try to find a job, but I feel like I'm getting ready to stop being a script-kiddie and actually get into more professional stuff.
What should I do?
Find vulnerabilities in software, the more widely used the better. Try both closed & open source software. Publish some CVEs. Different approaches can work depending on your preferred "style" but following a methodology (e.g. OWASP web security assessment guide, OWASP code review guide, or the approach from "The Art of Software Security Assessment") will reliably net bugs if you are persistent.
Team up - find groups adjacent to your interests and get involved. CTF teams are good for this, ideally you want somethings where you work together with others towards a common purpose.
Try some bug bounty programs. You will find you need some "unique" angle to be able to get anywhere. Even if you don't make any money (you might, you might not) it's a good excuse and the money is decent motivation to spend time looking for bugs on "real" websites. Find discords & slacks relevant to BB hunting and join them. Talk with people about it.
Get a certification. Yes, they suck. Optional. But if you have an industry cert and a detectable pulse you can probably get a job in computer security (whether it's one you want is another question, but it's an option to jam a foot in the door).
I dunno if this is on target for you, I made a lot of assumptions here about the size and shape of the dent you might want to make in the world.
Whatever you do, it helps to prioritise "visible" activities that produce concrete achievements that help you build a rep and a network. "Network" is kind of a sterile word but I couldn't think of a better one. The computer security industry is very "cliquey", it helps a lot to get involved in activities that help you get to know people, and make you "known" to others.
I don't have much advice for business lol.